1. Field of the Invention
The present invention relates to an image display unit for forming an image, and particularly relates to an image display unit having a voltage introducing terminal for applying a voltage to an anode electrode.
2. Related Background Art
In a conventional image display unit for displaying a dynamic image, etc., a CRT excellent in color reproducibility, responsive speed of an image, price, etc. has been widely used particularly as a color image display unit.
In contrast to this, the CRT has a defect in that the CRT is deep in depth with respect to a display area. Therefore, there is also conventionally a request for the image display unit of a planar type. In recent years, the image display unit of a planar type using a liquid crystal has spread instead of the CRT, but is not of a self light emission type. Therefore, problems exist in that the planar type image display unit must have a back light and field of view depends on angle, etc. Accordingly, the development of a display unit of the planar type and the self light emission type has been desired.
A color plasma display begins to be recently commercialized as such a planar type image display unit of self light emission. However, the principle of light emission in the color plasma display differs from that in the conventional CRT. Therefore, in the present situation, the color plasma display is slightly inferior to the CRT with respect to the contrast of an image, goodness of coloring, etc.
However, in the case of an image display unit using an electron beam similar to the CRT, it can be expected that an image quality equivalent to that in the CRT is obtained. Therefore, the planar type image display unit using the electron beam is researched and developed in many cases.
In these many planar type image display units using the electron beam, plural electron emitting devices of hot cathode and cold cathode types are arranged as a generating source of electrons (hereinafter, simply called an electron source) so that a deflecting space of the electron beam required in the CRT is reduced and the display unit is made thin and flat.
With respect to image display, these planar type image display units use the same principle as the CRT in which an electron emitted from the above electron source is accelerated by a high voltage and is irradiated to a phosphor. Accordingly, it is expected that an image quality similar to that in the CRT is obtained.
For example, Japanese Patent Application Laid-Open No. 4-163833 discloses a planar type image display unit using an electron beam and including a linear hot cathode and a complicated electrode constructional body within a vacuum container.
In these planar type image display units using the electron beam, for example, there is a case in which one portion of the electron beam incident to the phosphor is scattered and collides with an inner wall of the vacuum container, and a secondary electron is emitted and a charge is increased in this emitting portion. In this case, an internal electric potential distribution is distorted and an orbit of the electron beam becomes unstable. Further, an electric discharge is caused within the display unit so that there is a fear that the display unit is deteriorated and broken.
There is a method for forming a charging preventing film in the inner wall of the vacuum container as a method for preventing such an increase in charge. For example, Japanese Patent Application Laid-Open No. 4-163833 discloses a construction in which a conductive layer constructed by a conductive material of high impedance is arranged on a side face of the inner wall of a glass container of the image display unit.
In the image display unit using the electron beam, a high voltage for accelerating electrons is applied between the electron source and the phosphor.
Therefore, when the vacuum container of the image display unit is constructed by glass including Na such as a blue plate glass, etc., Na ions are moved by the above electric field and an electrolytic current is caused.
The vacuum container using glass is formed by joining plural members by frit glass. However, when Na ions flow into the frit glass by the above electrolytic current, PbO included in the frit glass is reduced and Pb is deposited. Accordingly, there is a fear that a crack is caused in the frit glass and no vacuum within the container can be held.
In contrast to this, there is a method in which an electrode is arranged in a suitable position of an outer wall of the vacuum container and an electrolytic current is absorbed into this electrode so that no electrolytic current flows into the frit glass.
For example, Japanese Patent Application Laid-Open No. 4-94038 shows a construction in which a conductive film of low resistance is arranged in a peripheral portion of a face plate and is set to a ground electric potential and no electrolytic current flows into the frit glass. U.S. Pat. No. 5,357,165 discloses a construction in which a band-shaped electrode for forming the gradient of an electric potential by flowing a current is arranged in a side wall of the vacuum container.
In contrast to this, in the planar type image display unit utilizing the above electron beam described in Japanese Patent Application Laid-Open No. 4-163833, the deflecting space of the electron beam required in the conventional CRT is greatly reduced by using plural linear hot cathodes. However, the complicated electrode constructional body such as a horizontal deflecting electrode, a vertical deflecting electrode, etc. for deflecting the electron beam to plural pixels (phosphor) is included within the container. Therefore, it cannot be avoided that the display unit has a certain thickness (about several ten mm). However, in recent years, for example, the development of a display unit of a super thinner type similar to that of a liquid crystal display is also required in the planar type image display unit utilizing the electron beam as a portable information terminal device, etc.
The present applicant already made many proposals with respect to a surface conduction electron emitting device and a planar type image display unit using this surface conduction electron emitting device to achieve the planar type image display unit of a super thin type utilizing the electron beam. For example, such proposals are described in Japanese Patent Application Laid-Open No. 7-235255.
This electron emitting device is simple in construction and many electron emitting devices can be integrated and formed in a large area. Therefore, one electron emitting device can be also formed with respect to one pixel (phosphor), land it is possible to remove the deflecting space of the electron beam required in the planar type image display unit utilizing the electron beam described in the above Japanese Patent Application Laid-Open No. 4-163833, or the normal CRT. Therefore, the electron emitting device can be used in a very thin planar type image display unit.
Further, a planar type image display unit of a super thin type using a field emitter type electron emitting device (hereinafter, called an FE type device) as the electron source is described in Japanese Patent Application Laid-Open No. 5-114372.
The planar type image display unit of a super thin type capable of relatively stably introducing a high voltage is shown by an introducing structure of the high voltage in the above-mentioned conventional display unit (FIG. 11). In accordance with FIG. 11, a face plate 2 is formed oppositely to a rear plate 1, and a low voltage electrode 12 for a wiring electrode for scanning and a wiring electrode for applying a signal voltage is formed in the electron emitting device in the rear plate 1. A phosphor, each layer of a metal back and a phosphor pull-out electrode 6 are formed in the face plate 2. A bar-shaped electrode 9 and an elastic body 28 connected to the bar-shaped electrode 9 from a side of the rear plate 1 are sequentially connected to this phosphor pull-out electrode 6. The bar-shaped electrode 9 is supported by an insulator 27 adhered by a frit glass 28 of an adhesive. The high voltage is supplied from this bar-shaped electrode 9 and is applied, to the phosphor pull-out electrode 6. An electron from the electron source having the electron emitting device on a side of the rear plate 1 is attracted and light emission of the phosphor is accelerated and an image is formed.
However, in the above planar type image display unit (FIG. 11) in the conventional example, elastic force of the elastic body using a metal is weakened by heat at a seal-attaching time and there is a case in which a connection defect is caused. There is also a case in which a small leak is caused since a seal body is formed later.
Further, a joining operation is performed in an interposing state of the adhesive between a voltage introducing terminal for introducing a voltage from the exterior of the vacuum container to an electrode on an inner surface of the face plate and the rear plate having the electron source constructed by the plural electron emitting devices formed on a planar substrate. Therefore, the planar type image display unit has the following problems.
The distance between the rear plate and the voltage introducing terminal is dispersed by melting irregularities of the adhesive. Accordingly, there is a case in which a defect in contact of a pull-out wiring formed in the face plate and a central electrode of the voltage introducing terminal is caused. Therefore, there is a case in which electric conduction with the face plate becomes unstable.
Since the distance between the rear plate and the voltage introducing terminal is dispersed by the melting irregularities of the adhesive, internal stress is caused in pressurization of the adhesive and heating burning and there is a case in which a slow leak due to a defect in seal attachment is caused after the seal attachment.
An object of the present invention is to provide an image display unit having a conductive path with good electric conduction to apply a voltage from the exterior of a container to an electric conductor within the container.
Another object of the present invention is to provide an image display unit connected in good condition to an electric conductor within a container and having an electric conductor for supplying a voltage from the exterior of the container to the electric conductor within the container.
Another object of the present invention is to provide an image display unit having a container sufficiently airtightly sealed and attached.
The present invention resides in an image display unit comprising: a container constructed by a member including first and second substrates spaced from each other; an electron source arranged on the first substrate within the container; an image display member arranged on the second substrate within the container and having a first electric conductor; and a second electric conductor coming in contact with the first electric conductor through a hole formed in the first substrate, the image display unit being characterized in that the second electric conductor has a holding member to the first substrate and the holding member has a portion coming in contact with the first substrate and a portion joined to the first substrate through an adhesive.
The present invention also resides in an image display unit comprising: a container constructed by a member including first and second substrates spaced from each other; an electron source arranged on the first substrate within the container; an image display member arranged on the second substrate within the container and having a first electric conductor; and a second electric conductor coming in contact with the first electric conductor through a hole formed in the first substrate, the image display unit being characterized in that the second electric conductor has a holding member to the first substrate and the holding member has a portion coming in contact with an outer surface of the first substrate and a portion joined to the outer surface of the first substrate through an adhesive.
The above image display unit of the present invention also includes that
the first substrate is a rear plate and the second substrate is a face plate,
the container is constructed by the first substrate, the second substrate and a supporting frame nipped by both the substrates,
the first electric conductor is an anode electrode,
the first electric conductor is a metal back,
the first electric conductor is a pull-out electrode electrically connected to the anode electrode or the metal back,
the image display member has the anode electrode or the metal back, and a phosphor,
the holding member is an insulator, and
the second electric conductor and the holding member constitute a voltage introducing terminal for applying a voltage to the first electric conductor.
The present invention also resides in an image display unit comprising: a rear plate having an electron source; a face plate arranged oppositely to the rear plate such that a phosphor emitting light by irradiating an electron beam emitted from the electron source and an anode electrode for applying a voltage to the phosphor are arranged on an inner surface of the face plate; a supporting frame nipped in side edge portions of the rear plate and the face plate and constituting one portion of a container together with the rear plate and the face plate; and a voltage introducing terminal for introducing a voltage from the exterior of the container to the anode electrode on the inner surface of the face plate, the image display unit being characterized in that the voltage introducing terminal has a central electrode and an insulator covering the circumference of the central electrode, and also has a portion coming in contact with the rear plate and a portion joined to the rear plate through an adhesive in a joining portion joined to the rear plate through a hole formed in the rear plate.
The above image display units of the present invention also include that
the voltage introducing terminal has the central electrode and the insulator covering the circumference of the central electrode, and also has a groove for arranging the adhesive in one portion of a portion coming in contact with the rear plate in the joining portion joined to the rear plate through the hole formed in the rear plate, and further has a portion joined to the rear plate through the adhesive,
the container is formed by adhering the insulator of the voltage introducing terminal to the hole formed in the rear plate,
the electron source has plural electron emitting devices, and
the electron emitting devices are cold cathode electron emitting devices.